Circuit interrupter



March 22, 1949. w, M LEEDS 2,465,240

CIRCUIT INTERRUPTER Filed Aug. 31, 1944 3 Sheets-Sheet 2 WITNESSES:lNVENTOR Mk/Zra J/{Zeaa I I 611 1/ ATTORNEY W. M. LEEDS CIRCUITINTERRUPTER March 22, 1949.

3 Sheets-Sheet 3 Filed Aug. 31, 1944 INVENTOR ATTORNE g x W 50 mviPatented Mar. 22, 1949 UNITED STATES PATENT OFFICE CIRCUIT INTERRUPTERWinthrop M. Leeds, Forest Hills, Pa., assignor to Westinghouse ElectricCorporation, East Pittsburgh, Pa.,- a corporation of PennsylvaniaApplication August 31, 1944, Serial No. 552,133

22 Claims. 1

This invention relates to circuit interrupters in general and, moreparticularly, to circuit interrupters of the liquid-break type. InUnited States patent application filed August 15, 1944, Serial No.549,576, by Winthrop M. Leeds and James M. Cumming, and assigned to theassignee of the instant invention, there is disclosed a novelcircuit-interrupting structure in which rotatable actuating means areemployed to effect simultaneous operation of the contact structures in aplurality of serially related superimposed arc-extinguishing units.

A general object of my invention is to provide an improved circuitinterrupter which will more effectively interrupt the electrical circuitthere through than has been achieved heretofore.

Another object is to provide an improved circuit interrupter comprisinga plurality of arcextinguishing units and to employ an improvedoperating arrangement for establishing two serially related arcs withineach arc-extinguishing unit. Preferably one of the arcs is apressuregenerating arc and. the other are is an interrupting are so thatfluid may flow from the pressuregenerating arc toward the interruptingarc ts facilitate the latters extinction.

Another object is to provide an improved circuit interrupter of theforegoing type in which. piston means are associated with the movablecontact means to assist in the interruption of low currents.

Another object is to provide an improved circuit interrupter in whichthe contact structure is such that there are no overlapping electricalpotentials, thus reducing the hazard of insulation breakdown within theinterrupter.

Another object is to provide an improved circuit interrupter comprisinga plurality of arcextinguishing units, in each of which stationarycontact means are disposed within the unit with which two movablecontacts movable toward each other come into engagement.

Another object is to provide an improved circuit interrupter of theforegoing type in which iston means associated with the contacts areemployed to facilitate low current interruption.

Another object is to provide an improved circuit interrupter comprisingan improved arcextinguishing unit within which is positoned a stationaryconducting plate. Preferably two movable contacts strike the plate inthe closed circuit position of the interrupter and rotatable actuatingmeans are employed for effecting the operation of each of the movablecontacts. In a preferred arrangement, both of the rotatable 2 actuatingmeans are simultaneously operated by longitudinal movement of anoperating rod extending externally of the several arc-extinguishingunits.

In the usual type of two break circuit interrupter in which oil underpressure from the pressure-generating break is sent downwardly along thesides of the intermediate contact toward the interrupting break toeffect the extinction of the interrupting arc, the vertical length alongthe sides of the relatively long intermediate contact is relied upon toprevent gas contamination of the oil forced into the interrupting arc.Such a vertical construction is shown, for example, in U. S. Patent2,406,469 issued August 27, 1946, to Leon R. Ludwig, Winthrop M. Leedsand Benjamin P. Baker, and assigned to the assignee of the instantapplication.

The vertical height of such a construction as set forth in theabove-mentioned patent does not readily lend itself to repeatable unitconstruction for higher voltage application because of the considerablevertical height required for a plurality of such units disposed inspaced superimposed relation and arranged for simultaneous operation.

It is, therefore, a further object of my invention to provide animproved arc extinguishing unit construction in which a relatively flatplate-like intermediate contact is utilized to diminsh vertical height,and to obtain the requisite length of oil travel by having an opening inpartition means disposed adjacent the intermediate plate at aconsiderable distance laterally from both the con" tacts which engagethe intermediate contact. This will provide the desired length of oilpassage by such a U-shaped passage construction around the partitionmeans, and yet the vertical height of such a relatively flat unit lendsitself to repeatable unit construction for the higher voltageapplications.

Still another object is to improve such a construction as set forth inthe preceding paragraph by having a non-alignment of the contacts whenengaging the intermediate plate contact with the opening through thepartition means off laterally to one side of both contacts. Preferably apiston. is employed to facilitate low current interruption.

Another object is to provide an improved operating mechanism for such arelatively fiat repeatable unit construction in which the movablecontacts are not aligned when in engagement with the plate typeintermediate contact.

Further objects and advantages will readily become apparent upon areading of the following specification taken in conjunction with thedrawings, in which:

Figure 1 is a vertical sectional view of an arcextinguishing assemblageembodying my invention and shown in the partially open circuit position;

Fig. 2 is a sectional view taken along the line 11-11 of Fig. 3 of amodified type unit construction;

Fig. 3 is a vertical sectional view through the modified type ofarc-extinguishing unit embodying my invention;

Fig. 4 is a sectional view taken along the line IV-lV of Fig. 5 of astill further modified type unit construction;

Fig. 5 is a vertical sectional view through the modified type ofarc-extinguishin unit embodying my invention;

Fig. 6 is an elevational view of two of the arcextinguishing assemblagesshown in Fig. 1 immersed in a liquid contained within a tank structure,the parts being shown in the closed circuit position;

Fig. 7 is a sectional view taken along the line VII-VII of Fig. 8 ofanother modified type unit construction;

Fig. 8 is a vertical sectional view through the modified type ofarc-extinguishing unit embodying my invention;

Fig. 9 is a sectional view on a reduced scale taken along the line IXIXof Fig. 8; and

Fig. 10 is a sectional view taken along the line X-X of Fig. 1.

Referring to the drawings, and more particularly to Figs. 1 and 6thereof, the reference numeral I generally designates anarc-extinguishing assemblage supported by a terminal stud 2 extendingthrough an insulating bushing 3 which is supported from the cover 4 of atank 5 in which a suitable arc-extinguishing fluid 6, in this instanceoil, is filled to the level I. A movable conducting bridging member 8,reciprocally operated by an insulating operating rod 9, serves toelectrically connect the arc-extinguishing assemblage I with a secondidentical arc-extinguishing assemblage I supported in like manner fromthe cover 4.

Referring more particularly to Fig. 1, it will be observed that thearc-extinguishing assemblage I comprises a plurality of, in thisinstance two, arc-extinguishing units generally designated by thereference numeral I which are positioned in spaced relation by suitablemeans well known in the art. Disposed intermediate the ends of each unitIII are stationary contact means and apertured partition meanscomprising a stationary conducting plate II which makes engagement inthe closed circuit position with movable contact means, in this instancecomprising a first or lower movable contact I2 and a second or uppermovable contact I3. The contacts I2, I3 are not aligned when inengagement with the plate II. The lower movable contacts I2 arepivotally supported at I4 to the right-hand end of a lever meansgenerally designated by the reference numeral I and pivotally operableabout a stationary pivot I6 intermediate the ends thereof. At theleft-hand end of the lever means I 5 pivotally supported thereto at I!is a piston member It. It will be noted that the second or upper movablecontact I3 associated with the lower arcextinguishing unit Ill moveswith the piston member I8 associated with the upper arc-extinguishingunit II].

The lever means I5 is rotated by vertical reciprocating motion of twoinsulating operating rods I9 (see Fig. 3) to which are clamped brackets29, the brackets 20 having pins 2I extending therethrough. The pins 2Ialso extend through the lever means I5 at an offcenter location so thatupward or closing movement of the operating rods I9 causes acounterclockwise rotation of the lever means I5 to thereby effect anengagement between the movable contacts I2, I3 and the stationary plateII.

During the opening operation the bridging member 8 moves downwardly topermit the accelerating compression springs 22 to force the operatingrods I9 downwardly thereby causing a clockwise rotation of the levermeans I5 about the pivots I6 to cause a separation between the movablecontacts I2, I3 and the stationary plate I I within eacharc-extinguishing unit Ill.

The separation between the movable contact I2 and the stationary plateII establishes a pressure-generating are 23 which serves to drive oil inthe direction indicated by the arrows through an opening II a in theplate II and toward the interrupting are 24 drawn between the movablecontact I3 and the stationary plate II. Splitter members, generallydesignated by the reference numeral 25, may be employed to more readilyeffect the extinction of the interrupting are 24 as it moves in thedirection of the vents 26.

It will be observed that with the construction shown gas contaminationof the oil forced into the interrupting are 24 is avoided by theposition of the opening Ila in the partition means II, which gives arelatively long U-shaped oil w passage between the arcs 23, 24. In manyprior constructions where the contacts are aligned, the length of theintermediate contact is considerable and consequently the verticalheight of prior art unit constructions prohibited their superimposed usefor higher voltage applications.

In my improved unit II] it will be noticed that the structure isrelatively fiat because of the use of the fiat plate II and the locationof the opening I Ia to give a U-shaped oil flow passage. Consequently Imay employ two or more such units in spaced superimposed relation andstill have very little height used up for the entire assemblage I.

Also, the non-alignment of the contacts I 2, I3 cooperates with theparticular lever means I5 employed and results in a considerable lateraldistance between the arcs 23, 24. This has the advantage, as indicatedbefore, in providing a sufilciently long oil flow passage between thetwo arcs to prevent gas contamination of oil forced into theinterrupting gap. This lateral distance is enhanced in the constructionshown by positioning the opening Ila off laterally to one side of bothcontacts I2, I3 to thereby obtain an increased length of U-shaped oilflow passage between the arcs 23, 24.

Further, the non-alignment of the contacts I2, I3 cooperating with theparticular lever operating means I5 shown permits the use of the pistonsI8 in alignment with the contacts I3 at the other end of the lever meansI5 from the contacts I2.

During the interruption of low currents when the pressure generated atthe pressure-generating are 23 is relatively low, the piston actionafforded by the upward moving piston member I8 will create the requisiteflow required for interruption of the interrupting are 24. Afterinterruption of the interrupting are 24 has occurred, and after theoperating rods I9 have reached their lowermost position, the conductingbridging member 8 separates from the disconnect fingers 21, associatedwith a cross-member 28 interconnecting the two operating rods I9, toprovide an isolating gap into the circuit. Electrostatic shields 29, 30and 3| may be employed to minimize corona formation.

It will be noted that each unit it is a duplicate or" the next unit,thus making this interrupter very adaptable to application at diirerentvoltages by using a proportional number of units ID. It will also benoted that a distinct advantage of this design is that theseries-connected arcs, 23, 24 are also in series in space, that is,there are no overlapping electrical potentials, thereby reducing thehazard of insulation breakdown. Furthermore, considerable mechanicalspeed of contact separation is obtained by connecting the operating rodsNJ to the lever means l at a shorter radius offcenter than the movingcontacts l2, 13. As a result, different ratios of speed of the pressurebreak to the interrupting break are easily obtainable. I have found thata 1:2 ratio gives very good test results. The piston members I8 for lowcurrent interruption may be added without appreciable complication ofthe operating mechanism.

By making the area of the low current piston l8 equal approximately tothe sum of the areas of moving contacts l2 and IS, the pressuredeveloped by the arcs will exert forces on the operating linkage whichare approximately balanced.

Figs. 2 and 3 show a modified type of arcextinguishing unit generallydesignated by the reference numeral 32 which may be used in place of thearc-extinguishing units ll! of Fig. 1. It will be noted that U-shapedinserts 33 composed of a suitable magnetic material, in this instanceiron, are employed in the lower portion of the unit 32 to effect alateral movement of the pressure-generating are 23. Also in the upperportion of the unit 32 U-shaped magnetic inserts 34 may also be used tobias the interrupting are 24 toward vents 35 provided in insulatingplates 36 having a configuration more clearly shown in Fig. 2. Themagnetic inserts 34 are positioned in insulating plates 31 betweenadjacent insulating plates 38 of the same shape. The plates 37, 38provide a restricted slot 39 (Fig. 2) into which the interrupting are 24may be biased by the inserts 34 only during relatively low instantaneousvalues of arcing current, that is, near a current zero. The oil flowfrom the pressure are 23 toward the interrupting are 24 is as indicatedby the arrows.

The provision of magnetic means for efiecting the lateral movement ofthe pressure-generating are 23 increases the pressure formed thereat.The concept of laterally moving the pressuregenerating are by magneticmeans is disclosed and claimed in United States patent applicationSerial No. 471,847, filed January 9, 1943, by Benjamin P. Baker, nowPatent No. 2,412,857, granted December 1'7, 1946, and assigned to theassignee of the instant application. Also the magnetically biasing ofthe interrupting are N toward the vents 35 coupled with the oil flowfrom the pressure-generating are 23 rapidly effects the extinction ofthe interrupting are 24.

Figs. 4 and 5 show another modified type of arc extinguishing unitgenerally designated by the reference numeral 52. In this embodiment ofmy invention the interrupting are 24 is drawn in a widened slot 43, butis biased to the right away from the vents M by U-shaped inserts 45composed of magnetic material and being positioned as shown more clearlyin Fig. 4. The provision of the inserts 45 biases the interrupting are24 away from the vents 44 only during rela tively high instantaneousvalues of arcing cur rent, but near a current zero the biasing forcedecreases to permit oil flow from the pressuregenerating are 23 to carrythe interrupting are 24 into the restriction adjacent the vents M toeffect its extinction at an early current zero.

Figs. 7 through 9 show another embodiment of my invention. A modifiedtype of arc-extinguishing unit generally designated by the referencenumeral 53 is provided at the upper end of which is employed an arcinghorn 49 thus permitting extensive lateral movement of the interruptingarc M to the left. U-shaped magnetic inserts Eli are employed to effecta lateral movement of the pressure-generating are 23 to increase theprcssure formed thereat. U-shaped inserts 5i composed of a suitablemagnetic material are provided to bias the interrupting are 24 towardthe left along the arcing horn 39 and plate il into a taperingrestriction 52 provided by groups of plates, each group including aninsulating plate 53 containing the magnetic insert iii and twoadjacently disposed insulating guard plates 5d of the same shape.Insulating vent plates 55 having a configuration more clearly shown inFig. 7 are provided with oil pockets along the arc slot and. openings topermit the oil to vent out of the unit 48. An opening ii?) is providedadjacent the partition means it disposed intermediate the ends of theunit 18. The long slot provided for are motion permits the magneticfield to keep the are moving up to the boundary of the advancing gasbubble where the turbulent deionizing action is a maximum. This assuresarc interruption at the first currenzero after the arc moves off contact13 onto the arcing horn 49.

In the several embodiments of my invention, insulating tie rods 56 mayemployed to hold the several plates fixedly in position, and pref erablythe o crating rods l9 extend through tie arc-extinguishing units.

From the foregoing description it will be apparent that I have providedan improved interrupter comprising a plurality of arc-extinguishingunits in spaced relation without overlapping electrical potentials, ineach of which a pressuregenerating arc is established to drive oiltoward an interrupting arc, the oil flow being supplemented by a pistonfor low current interruption. Preferably I employ magnetic means toeffect a lateral movement of one or both of the arcs drawn in eacharc-extinguishing unit to accelerate and intensify the interruptingaction.

It will also be apparent from the foregoing description of severalembodiments of my invention that I have provided an improved relativelyflat arc extinguishing unit construction readily adaptable for highervoltage applications without using much vertical space. The constructionis such that a relatively great distance is provided between the arcs 26by having the contacts l2, l3 disposed laterally apart. Thisnonalignment of the movable contacts l2, l3 cooperates with theoperating mechanism disclosed including the rotatabe lever means it, andthe employment or U-shaped oil new pasthrough the partition means i iand interconnecting the arcs 23, N in such manner as to prevent gascontamination of the oil sent toward the interrupting are 24 to efiectthe lat ters extinction.

It will furthermore be observed that by the provision of thenon-alignment of the movable contacts I2, l3 with the rotatable levermeans i5 employed to efiect their operation, advantage may be taken ofone end of the lever means to cause actuation of the piston members H),which by their position, do not interfere with motion of their adjacentlaterally disposed companion movable contact members 12.

Also the simultaneous separation of the con tacts l2, l3 from theintermediate plates H causes simultaneous drawing of thepressuregenerating arcs 23 and the interrupting arcs 2d. Thus theassemblage I is high speed in operation and may be used for high speedbreaker application.

It will be apparent to those skilled in the art that variousinterrupting structures may be employed for effecting extinction of theinterrupting arc 24. However, I do not desire my invention to beconfined to the particular plate interrupting structures herein setforth, as certain broad structural positioning features of my inventiontogether with the operating mechanism cooperating therewith are of Widescope and application.

Although I have shown and described specific structures, it is to beclearly understood that the same were merely for purposes ofillustration and that changes and modifications may readily be madetherein by those skilled in the art without departing from the spiritand scope of the appended claims.

I claim as my invention:

1. In a circuit interrupter, two arc-extinguishing units, stationarycontact means disposed in each unit intermediate the ends thereof, levermeans disposed between the two units, means pivotally mounting the levermeans intermediate the ends thereof, means for rotating the lever meansduring the opening and closing operations, a movable contact linked toeach end of the lever means, the two movable contacts being movable inopposite directions and into engagement with one side of the stationarycontact means disposed in the two units, and means for establishing aserially related are on the other side of the stationary contact meansin at least one of the units.

2. In a circuit interrupter, a first and a second arc-extinguishingunit, stationary contact means disposed in each unit intermediate theends thereof, lever means disposed between the two units, meanspivotally mounting the lever mean intermediate the ends thereof, meansfor rotating the lever means during the opening and closing operations,a first contact linked to one end of the lever means and movable intothe first unit into engagement with the stationary contact meansdisposed therein, a second contact linked to the other end of the levermeans and movable into the second unit into engagement with thestationary contact means positioned therein, means including thestationary contact means for establishing a second serially related arcin one of the two units, and a piston member forming an extension of thesecond contact and movable during the opening operation into the firstunit to assist during low current interruption.

3. In a circuit interrupter, two arc-extinguishing units, stationarycontact means disposed in each unit intermediate the ends thereof, levermeans disposed between the two units, a movable contact linked to eachend of the lever means, the two movable contacts being movable inopposite directions and into engagement with the stationary contactmeans disposed in the two units, means for pivotally mounting the levermeans intermediate the ends thereof, means including the stationarycontact means in each unit for establishing a second serially relatedarc in each unit, and an operating rod extending longitudinally of theunits and pivotally connected to the lever means to cause the rotationthereof.

l. In a circuit interrupter, a first and a second arc-extinguishingunit, stationary contact means disposed in each unit intermediate theends thereof, lever means disposed between the two units, means forrotating the lever means during the opening and closing operations, afirst contact linked to one end of the lever means and movable into thefirst unit into engagement with the stationary contact means disposedtherein, a second contact linked to the other end of the lever means andmovable into the second unit into engagement with the stationary contactmeans positioned therein, a piston member forming an extension of thesecond contact and movable during the opening operation into the firstunit to assist during low current interruption, means for pivotallymounting the lever means intermediate the ends thereof, means includingthe stationary contact means in each unit for establishing a secondserially related arc in each unit, and an operating rod extendinglongitudinally of the units and pivotally connected to the lever meansto cause the rotation thereof.

5. In a circuit interrupter, a first and a second arc-extinguishingunit, stationary contact means disposed in each unit intermediate theends thereof, lever means disposed between the two units, meanspivotally mounting the lever means intermediate the ends thereof, meansfor rotating the lever means during the opening and closing operations,a movable contact linked to each end of the lever means, the two movablecontacts being movable in opposite directions and into engagement withthe stationary contact mean-s disposed in the two units, second levermeans positioned on the other side of the second unit, and a movablecontact linked to one end of the second lever means and movable duringthe closing operation into engagement with the stationary contact meansdisposed in the second unit.

6. In a circuit interrupter, a first and a second arc-extinguishingunit, stationary contact means disposed in each unit intermediate theends thereof, lever means disposed between the two units, means forrotating the lever means during the opening and closing operations, amovable contact linked to each end of the lever means, the two movablecontacts being movable in opposite directions and into engagement withthe stationary contact means disposed in the two units, second levermeans positioned on the other side of the second unit, a movable contactlinked to one end of the second lever means and movable during theclosing operation into engagement with the stationary contact meansdisposed in the second unit, means pivotally mounting both lever meansintermediate the ends thereof, and an operating rod extendinglongitudinally of the units and pivotally connected to both lever meansto cause the rotation thereof.

'7. In a circuit interrupter, a first and a second arc extinguishingunit, stationary contact means disposed in each unit intermediate theends thereof, lever means, disposed between the two. units, means forrotating the lever means during, the opening, and closing operations, amovable contact linked to each end of the lever means, the two movablecontacts being movable in opposite directions and into engagement withthe stationary contact means, disposed in the two units, second levermeans positioned on the other side'of the second unit, a movable contactlinked to one end of the second lever means and mov-- able during theclosing operation into engagement with the stationary contact meansdisposed in the second unit, means pivotally mounting the first andsecond lever means intermediate the ends thereof, and a piston memberlinked to the other end of the second lever means and movable into thesecond unit during the opening operation.

8. In a circuit interrupter, a first and a second arc-extinguishingunit, stationary contact means disposed in each unit intermediate theends thereof, lever means disposed between the two units, means forrotating the lever means during the opening and closing operations, amovable contact linked to each end of the lever means, the two movablecontacts being movable in opposite directions and into engagement withthe stationary contact means disposed in the two units, second levermeans positioned on the other side of the second unit, a movable contactlinked to one end of the second lever means and movable during theclosing operation into engagement with the stationary contact meansdisposed in the second unit, means pivotally mounting both lever meansintermediate the ends thereof, an operating rod extending longitudinallyof the units and pivotally connected to both lever means to cause therotation thereof, and a piston member linked to the other end of thesecond lever means and movable into the second unit during the openingoperation.

9. In a circuit interrupter, a first and a second arc-extinguishingunit, stationary contact means disposed in each unit intermediate theends thereof, lever means disposed between the two units, meanspivotally mounting the lever means intermediate the ends thereof, meansfor rotating the lever mean-s during the opening and closing operations,a first contact linked to one end of the lever means and movable intothe first unit into engagement with the stationary contact meansdisposed therein, a second contact linked to the other end of the levermeans and movable into the second unit into engagement with the stationary contact means positioned therein, a piston member forming anextension of the second contact and movable during the opening operationinto the first unit to assist during low current interruption, secondlever means disposed on the other side of the second unit, and a firstcontact linked to one end of the second lever means and movable intoengagement with the stationary contact means disposed in the secondunit.

10. In a circuit interrupter, a first and a second arc-extinguishingunit, stationary contact means disposed in each unit intermediate theends thereof, lever means disposed between the two units, means forrotating the lever means during the opening and closing operations, afirst contact linked to one end of the lever means and movable into thefirst unit into engagement with the stationary contact means disposedtherein, a second contact linked to the other end of the lever means andmovable into the second unit into engagement with the stationary contactmeans positioned therein, a piston member forming an extension of thesecond contact and movable during the opening operation into the firstunit to assist during low current interruption, second lever meansdisposed on the otherside of the second unit, a first contact linked toone end of the second lever means and movable into engagement with thestationary contact means disposed in the second unit, means pivotallymounting the two lever means intermediate the ends thereof, and anoperating rod extending longitudinally of the units and pivotallyconnected to the two lever means to cause the rotation thereof.

11. In a circuit interrupter, a first and a second arc-extinguishingunit, stationary contact means disposed in each unit intermediate theends thereof, lever means disposed between the two units, means forrotating the lever means during the opening and closing operations, afirst contact linked to one end of the lever means and movable into thefirst unit into engagement with the static-nary contact means disposedtherein, a second contact linked to the other end of the lever means andmovable into the second unit into engagement with the stationary contactmeans positioned therein, a piston member forming an extension of thesecond contact and movable during the opening operation into the firstunit to assist during low current interruption, second lever meansdisposed on the other ,side of the second unit, means pivotally mountingthe first and second lever means intermediate the ends thereof, a firstcontact linked to one end of the second lever means and movable intoengagement with the stationary contact means disposed in the secondunit, and a second piston member linked to the other end of the secondlever means and movable into the second unit during the openingoperation to assist during .ow current interruption.

12. In a circuit interrupter, a first and a second arc-extinguishingunit, stationary contact means disposed in each unit intermediate theends thereof, lever means disposed between the two units, means forrotating the lever means during the opening and closing operations, afirst contact linked to one end of the lever means and movable into thefirst unit into engagement with the stationary contact means disposedtherein, a second contact linked to the other end or" the lever meansand movable into the second unit into engagement with the stationarycontact means positioned therein, a piston member fOI'-1 ing anextension of the second contact and movable during the opening operationinto the first unit to assist during low current interruption, secondlever means disposed on the other side of the second unit, a firstcontact linked to one end or" the second lever means and movable intoengagement with the stationary contact means disposed in the secondunit, a second piston member linked to the other end of the second levermeans and movable into the second unit during the opening operation toassist during low current interruption, means pivotally mounting the twolever means intermediate the ends thereof, and an operating rodextending longitudinally of the units and pivotally connected to the twolever means to cause the rotation thereof.

13. In a circuit interrupter, a substantially enclosed arc extinguishingunit, a conducting plate positioned intermediate the ends of the unit,the unit defining a pressure-generating chamber on one side of the plateand an interrupting chamber on the other side of the plate, contactmeans including a pair of movable contacts simultaneously separable fromthe conducting plate to simultaneously establish a pressure-generatingarc within the pressure-generating chamber and an interrupting arewithin the interrupting chamber, the pair of contacts being non-alignedwhen in the closed circuit position, and a U-shaped fluid flow passagemeans interconnecting the two chambers so that fluid under pressure fromthe pressure-generating arc may fiow under pressure through the passagemeans into the interrupting chamber to effect the extinction of theinterrupting are disposed therein.

14. In a circuit interrupter, a substantially enclosed arc extinguishingunit, a conducting plate positioned intermediate the ends of the unit,the unit defining a pressure-generating chamber on one side of the plateand an interrupting chamber on the other side of the plate, contactmeans including a pair of movable contacts simultaneously separable fromthe conducting plate to simultaneously establish a pressure-generatingarc within the pressure-generating chamber and an interrupting arewithin the interrupting chamber, the pair of contacts being non-alignedwhen in the closed circuit position, a pair of lever means disposed onopposite sides of the unit for operating the contact means, meanspivotally mounting each of the lever means intermediate the endsthereof, each of the movable contacts being operatively connectedadjacent one end of each lever means, passage means interconnecting thetwo chambers so that fluid under pressure from the pressure-generatingarc may flow under pressure through the passage means into theinterrupting chamber to effect the extinction of the interrupting arcdisposed therein.

15. In a circuit interrupter, a substantially enclosed arc extinguishingunit, a conducting plate positioned intermediate the ends of the unit,the unit defining a pressure-generating chamber on one side of the plateand an interrupting chamber on the other side of the plate, contactmeans including a pair of movable contacts simultaneously separable fromthe conducting plate to simultaneously establish a pressure-generatingarc within the pressure-generating chamber and an interrupting arewithin the interrupting chamber, the pair of contacts being non-alignedwhen in the closed circuit position, a U-shaped fluid flow passage meansinterconnecting the two chambers so that fluid under pressure from thepressure-generating arc may flow under pressure through the passagemeans into the interrupting chamber to effect the extinction of theinterrupting arc disposed therein, a piston chamber disposed closelyadjacent to the path of movement of one of the movable contacts, and apiston member movable within the piston chamber to facilitate lowcurrent interruption.

16. In a circuit interrupter, a substantially enclosed arc extinguishingunit, a conducting plate positioned intermediate the ends of the unit,the unit defining a pressure-generating chamber on one side of the plateand an interrupting chamber on the other side of the plate, contactmeans including a pair of movable contacts simultaneously separable fromthe conducting plate to simultaneously establish a pressure-generatingare within the pressure-generating chamber and an interrupting arewithin the interrupting chamber, the pair of contacts being non-alignedwhen in the closed circuit position, a pair of lever means disposed onopposite sides of the unit for operating the contact means, meanspivotally mounting each of the lever means intermediate the endsthereof, each of the movable contacts being operatively connectedadjacent one end of each lever means, passage means interconnecting thetwo chambers so that fluid under pressure from the pressure-generatingarc may flow under pressure through the passage means into theinterrupting chamber to efiect the extinction of the interrupting aredisposed therein, a piston chamber disposed closely adj acent to thepath of movement of one of the movable contacts, and a piston membermovable within the piston chamber to facilitate low currentinterruption.

17. In a circuit interrupter of the liquid break type, a substantiallyenclosed arc extinguishing unit submerged within the liquid, operatingmeans for the unit including a pair of lever means positioned onopposite sides of the unit, means pivotally mounting each of the levermeans intermediate the ends thereof, a movable contact linked adjacentone end of each of the two lever means and movable within the unit, aconducting plate positioned intermediate the ends of the unit with whichthe two movable contacts make non-aligning engagement, the unit defininga pressure-generating chamber adjacent to the path of movement of one ofthe movable contacts, the unit clefining an interrupting chamberadjacent to the path of movement of the other movable contact, andpassage means interconnecting the two chambers so that liquid underpressure from the pressure-generating chamber may flow through thepassage means and into the interrupting chamber to effect the extinctiontherein of the interrupting arc.

18. In a circuit interrupter of the liquid break type, a substantiallyenclosed arc extinguishing unit submerged within the liquid, operatingmeans for the unit including a pair of lever means positioned onopposite sides of the unit, means pivotally mounting each of the levermeans intermediate the ends thereof, a movable contact linked adjacentone end of each of the two lever means and movable within the unit, aconducting plate positioned intermediate the ends of the unit with whichthe two movable contacts make non-aligning engagement, the unit defininga pressuregenerating chamber adjacent to the path of movement of one ofthe movable contacts, the unit defining an interrupting chamber adjacentto the path of movement of the other movable contact, passage meansinterconnecting the two chambers so that liquid under pressure from thepressure-generating chamber may flow through the passage means and intothe interrupting chamber to effect the extinction therein of theinterrupting are, a piston chamber disposed adjacent the path ofmovement of one of the two movable contacts, and a piston memberoperatively linked adjacent the other end of one of the two lever meansand movable within the piston chamber to facilitate low currentinterruption.

19. In a circuit interrupter of the liquid break type, a substantiallyenclosed arc extinguishing unit submerged within the liquid, operatingmeans for the unit including a pair of lever means positioned onopposite sides of the unit, means pivotally mounting each of the levermeans intermediate the ends thereof, a movable contact linked adjacentone end of each of the two lever means and movable within the unit, aconducting plate positioned intermediate the ends of the unit with whichthe two movable contacts make non-aligning engagement, the unit defininga pressure-gencrating chamber adjacent to the path of movement of one ofthe movable contacts, the unit defining an interrupting chamberadjacent'to the path of movement of the other movable contact. passagemeans interconnecting the two chambers so that liquid under pressurefrom the pressuregenerating chamber may flow through the passage means.and into the interrupting chamber to effect the extinction therein ofthe interrupting arc, a piston chamber disposed adjacent the path ofmovement of the pressure-generating contact, and a piston memberoperatively linked adjacent the other end of one of the two lever meansand movable within the piston chamber to facilitate low currentinterruption.

20. In a circuit interrupter, a substantially enclosed arc extinguishingunit, a conducting plate positioned intermediate the ends of the unit,the unit defining a pressure-generating chamber on one side of the plateand an interrupting chamber on the other side of the plate, contactmeans including a pair of movable contacts simultaneously separable fromthe conducting plate to simultaneously establish a pressure-generatingare within the pressure-generating chamber and an interrupting arewithin the interrupting chamber, the pair of contacts being non-alignedwhen in the closed circuit position, a pair of lever means disposed onopposite sides of the unit for operating the contact means, meanspivotally mounting each of the lever means intermediate the endsthereof, each of the movable contacts being operatively connectedadjacent one end of each lever means, passage means interconnecting thetwo chambers so that fluid under pressure from the pressure-generatingarc may flow under pressure through the passage means into theinterrupting chamber to effect the extinction of the interrupting aredisposed therein, a piston chamber disposed closely adjacent to the pathof movement of one of the movable contacts, a piston member movablewithin the piston chamber to facilitate low current interruption, andthe piston member being operatively connected adjacent the other end ofone of the two lever means.

21. In a circuit interrupter, a substantially enclosed arc extinguishingunit, a conducting plate positioned intermediate the ends of the unit,the unit defining a pressure-generating chamber on one side of the plateand an interrupting chamber on the other side of the plate, contactmeans including a pair of movable contacts simultaneously separable fromthe conducting plate to simultaneously establish a pressure-generatingare within the pressure-generating chamber and an interrupting arewithin the interrupting chamber, the pair of contacts being non-alignedwhen in the closed circuit position, a pair of lever means disposed onopposite sides of the unit for operating the contact means, meanspivotally mounting each of the lever means intermediate the endsthereof, each of the movable contacts being operatively connectedadjacent one end of each lever means, passage means interconnecting thetwo chambers so that fluid under pressure from the pressure-generatingarc may flow under pressure through the passage means into theinterrupting chamber to effect the extinction of the interrupting aredisposed therein, a piston chamber disposed closely adjacent to the pathof movement of the pressure-generating contact, and a piston membermovable within the piston chamber to facilitate low circuitinterruption.

22. In a circuit interrupter, a substantially enclosed arc extinguishingunit, a conducting plate positioned intermediate the ends of the unit,the unit defining a pressure-generating chamber on one side of the plateand an interrupting chamber on the other side of the plate, contactmeans including a pair of movable contacts simultaneously separable fromthe conducting plate to simultaneously establish a pressure-generatingarc within the pressure-generating chamber and an interrupting arewithin the interrupting chamber, the pair of contacts being non-alignedwhen in the closed circuit position, a pair of lever means disposed onopposite sides of the unit for operating the contact means, meanspivotally mounting each of the lever means intermediate the endsthereof, each of the movable contacts being operatively connectedadjacent one end of each lever means, passage means interconnecting thetwo chambers so that fluid under pressure from the pressure-generatingarc may fiow under pressure through the passage means into theinterrupting chamber to efiect the extinction of the interrupting aredisposed therein, a piston chamber disposed closely adjacent to the pathof movement of the pressure-generating contact, a piston member movablewithin the piston chamber to facilitate low circuit interruption, andthe piston member being operatively connected adjacent the other end ofone of the two lever means.

WINTHROP M. LEEDS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,081,119 Johnson Dec. 9, 19131,645,905 Gregory et al Oct. 28, 1927 1,914,137 Leeds June 13, 19331,991,901 Leeds Feb. 19, 1935 2,039,054 Boden et al Apr. 28, 19362,147,497 Prince et a1 Feb. 14, 1939 2,155,263 Flurscheim Apr. 18, 19392,192,772 MacNeill Mar. 5, 1940 2,214,620 Leeds Sept. 10, 1940 2,292,547Sadler Aug. 11, 1942 2,372,589 Leeds et a1 Mar. 27, 1945 2,394,046Dickinson Feb. 5, 1946 FOREIGN PATENTS Number Country Date 486,050 GreatBritain May 30, 1938

